Sialidase or neuraminidase (EC 18.104.22.168) of Influenza viruses A and B
Sialidases or neuraminidases function to bind and hydrolyze terminal sialic acid residues from various glycoconjugates. Viral neuraminidases, such as this family from Influenza viruses A and B, play a vital role in pathogenesis. Influenza neuraminidase cleaves an alpha-ketosidic linkage between sialic acid and a neighboring sugar residue. During budding of virus particles from the infected cell, the sialidase helps to prevent the newly formed viral particles from aggregating. The viral sialidase cleaves terminal sialic acid from glycan structures on the infected cell surface, promoting virus release and the spread of virus to neighboring cells that are not yet infected. Also, sialidase modifies mucins in the respiratory tract and may improve access of the viral particle to its target cells. Sialidases have a six-bladed beta-propeller fold.